The area around the young man's Reudnitz-Thonberg-district home – about one kilometre away from where Michelle was found dead – was sealed off and searched by police after he went to police on Sunday.
Michelle went missing after playing with friends on August 18, 2008. Three days later her body was found by a local resident out for a walk.
Despite thousands of tips, police found few clues leading to the murderer. Police have questioned more than 1,000 witnesses and investigated 1,700 leads, collecting some 5,200 pieces of evidence. The 75-officer special investigation team has also taken voluntary saliva DNA samples from friends, neighbours and relatives of the girl.